May 31, 2013

New Graphene Camera Sensor Takes Better Dim-Light Photos

A new camera sensor invented by a team at Nanyang Technological University (NTU) will reportedly allow for even clearer low-light images.

The new graphene-based sensor is believed to be the first capable of detecting broad spectrum light, from the visible to mid-infrared, with high photoresponse or sensitivity. In other words, this sensor will open up opportunities to take better photos in dim conditions for all sorts of applications, including infrared cameras, traffic speed cameras, satellite imaging and more.

The researchers said their graphene sensor is 1,000 times more sensitive to light than current imaging sensors found in today's cameras. The sensor also uses 10 times less energy and the cost is at least five times cheaper.

Assistant Professor Wang Qijie, from NTU´s School of Electrical & Electronic Engineering, says this is the first time a broad-spectrum, high photosensitive sensor has been developed using pure graphene. Graphene is a million times smaller than the thickest human hair and is made of pure carbon atoms arranged in a honeycomb structure. It is known to have a high electrical conductivity.

“We have shown that it is now possible to create cheap, sensitive and flexible photo sensors from graphene alone. We expect our innovation will have great impact not only on the consumer imaging industry, but also in satellite imaging and communication industries, as well as the mid-infrared applications,” said Wang, who also holds a joint appointment in NTU´s School of Physical and Mathematical Sciences.

Qijie came up with an idea to create nanostructures on graphene to "trap" light-generated electron particles for a much longer time. He knew that these electric signals could then be processed into an image, like a photograph captured by a digital camera. These "trapped electrons" is the key to high photoresponse in graphene.

“The performance of our graphene sensor can be further improved, such as the response speed, through nanostructure engineering of graphene, and preliminary results already verified the feasibility of our concept,” said Wang, who published his breakthrough in the journal Nature Communications.

He said they had to keep current manufacturing practices in mind while designing their new camera sensor.

"This means the industry can in principle continue producing camera sensors using the CMOS (complementary metal-oxide-semiconductor) process, which is the prevailing technology used by the majority of factories in the electronics industry," Qijie said. "Therefore manufacturers can easily replace the current base material of photo sensors with our new nano-structured graphene material.”

According to Wang, once the new sensors are adopted by the industry, the cost of manufacturing will begin to drop, leading to cheaper cameras with a longer battery life.

Graphene is opening up a world of opportunities for future devices. Researchers just wrote in the Journal of Physical Chemistry Letters that they developed a graphene-based ink that could pave the way to creating foldable electronic devices. The team's method could open up the door to devices like bendable smartphones or tablets one day.